Wall-to-lumen ratio of retinal arterioles is related with urinary albumin excretion and altered vascular reactivity to infusion of the nitric oxide synthase inhibitor N-monomethyl-L-arginine

Objective We hypothesized that wall-to-lumen ratio (WLR) of retinal arterioles might serve as an in-vivo parameter of vascular damage. To test this hypothesis we examined whether WLR of retinal arterioles is related with increased urinary albumin excretion and altered vascular reactivity to infusion of the nitric oxide synthase inhibitor N-monomethyl-L-arginine (L-NMMA). Methods Thirty-nine never-treated male patients aged 18-65 years with a body mass index at least 25 kg/m² and without diabetes mellitus or secondary or stage 3 arterial hypertension were examined. WLR of retinal arterioles was assessed using scanning laser Doppler flowmetry. Urinary albumin-to-creatinine ratio (UACR) was measured from first morning spot urine. Vascular reactivity was measured by the change of aortic augmentation index (aAlx) to infusion of L-NMMA. Results UACR was related with WLR of retinal arterioles (r = 0.352, P= 0.032). In response to L-NMMA infusion aAlx increased (from 10.7±11 to 19.7±11%, P<0.001). The change of aAlx to L-NMMA infusion was inversely related with WLR of retinal arterioles (r= -0.462, P= 0.003) even after adjustment for changes of hemodynamic parameters to L-NMMA infusion (partial r= -0.475, P= 0.005). The relationships of UACR and the change of aAlx to L-NMMA infusion with WLR of retinal arterioles were found to be independently of other cardiovascular risk factors (ß = 0.386, P = 0.006; B = -0.369, P = 0.004, respectively) in multiple regression analyses with separate models for both parameters. Conclusion Increased WLR of retinal arterioles may thus serve as an in-vivo marker of vascular